in a class test + 3 marks are given for every correct answer and minus 2 marks are given for every in correct answers and no marks for no not attending any question first Radhika score 20 marks if she got 12 correct how many questions has she attend incorrectly second Mohini scores - 5 marks in this test though got 7 correct answer how many questions sheattempt in correctly
Answers
Marks obtained for 1 right answer = +3
Marks obtained for 1 wrong answer = −2
(i) Marks scored by Radhika = 20
Marks obtained for 12 correct answers = 12 × 3 = 36
Marks obtained for incorrect answers = Total score − Marks obtained for 12 correct answers = [20 − 36] = −16
Marks obtained for 1 wrong answer = −2
Thus, number of incorrect answers = (−16) ÷(−2) = 8
Therefore, she attempted 8 questions wrongly.
(ii) Marks scored by Mohini = −5
Marks obtained for 7 correct answers = 7 × 3 = 21
Marks obtained for incorrect answers = [Total score − Marks obtained for 12 correct answers] = [− 5 − 21] = −26
Marks obtained for 1 wrong answer = −2
Thus, number of incorrect answers = (−26) ÷(−2) = 13
∴, she attempted 13 questions wrongly.ANS
(iii) Total marks scored by Rakesh = 18
Number of questions attempted = 16
(Number of correct answers)(3) + (Number of incorrect answers)(−2) = 18
⇒(Number of correct answers)(3) + (16 − Number of correct answers)(−2) = 18
⇒(Number of correct answers)(3) + −32 + 2(Number of correct answers) = 18
⇒(Number of correct answers)(5) + −32 = 18
⇒(Number of correct answers)(5) = 18 + 32 = 50
⇒ Number of correct answers = 10
∴Number of incorrect answers = 16 − 10 = 6
∴Total number of correct and incorrect answers scored by Rakesh is 10 and 6 respectively.ANS
i)(20-12)
=8/2 = 4
ii)21+5 /
=26/2
=13